Battery with through-hole

Abstract: A battery has a through-hole traversing a battery main body and opened to outside. The battery has a vessel having a central through-hole, and a spiral-shaped electrode, made up of a strip-shaped positive electrode and a strip-shaped negative electrode wound about a cylindrical core a number of times with a separator in-between, is mounted in the battery vessel so that an opening of the cylindrical core is substantially coincident with the through-hole in the battery vessel. The battery vessel is sealed after charging a liquid electrolyte. One or more thin metal plates are inserted and secured in the through-hole, or one or more heat-dissipating fins are radially formed around the opening end of the through-hole. The battery has good heat-dissipating properties and is superior in strength and energy density.

Description: BACKGROUND OF THE INVENTION This invention relates to a battery according to the preamble of claim 1. As an example of such a prior-art battery, a battery having a through-hole is discloded in US-A-4,262,064 (or FR-A-53 670). Such a battery is subject to storage of heat and rise in temperature due to the heat of reaction of the electrodes resulting from charging/discharging and the Joule heat by the current flowing through the electrodes or the current collectors. Such phenomenon becomes outstanding when the battery is increased in size. For combatting such phenomenon, a cooling fluid may be caused to flow through the through-hole of the battery or through a passage for a cooling fluid (EP-A-0 044 753). However, the energy density of the electric source system in its entirety is lowered due to the increase in volume or weight caused by the provision of the cooling system. SUMMARY OF THE INVENTION It is an object of the present invention to provide a battery whereby the problem of temperature rise may be overcome without decreasing the energy density or mechanical strength. For accomplishing the above object, the present invention provides a battery in which a through-hole traversing a main battery body and opened to outside is formed at a central region of the main battery body, wherein at least one thin metal plate is inserted and secured within the through-hole. According to the present invention, only the through-hole and at least one thin metal plate is inserted and secured within the through-hole is formed as heat dissipating means, while there is no necessity of providing complex cooling means for heat dissipation. Consequently, the energy density is not lowered due to the weight or the capacity of the cooling means. Also, the surface area of the battery may be maintained without the necessity of using a planar or elongated shape of the battery, so that the battery itself is not lowered in strength. Also by forming heat dissipating fins around the opening end of the through-hole, heat dissipation may be improved further, whereas the heat generated by charging/discharging of large current may be efficiently dissipated. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic perspective view showing an embodiment of a columnar-shaped battery according to the present invention, but without showing the thin metal plates in the through-hole. Fig. 2 is a schematic cross-sectional view showing the inner structure of the columnar-shaped battery shown in Fig.1 during the fabrication process. Fig. 3 is a plan view showing the state in which a thin metal plate is mounted in a through-hole. Fig. 4 is a plan view showing the state in which two thin metal plates are mounted in a through-hole. Fig. 5 is a plan view showing the state in which four thin metal plates are mounted in a through-hole. Fig. 6 is a plan view showing the state in which six thin metal plates are mounted in a through-hole. Fig. 7 is a side view showing a sealing plate having a heat-dissipating fin. DESCRIPTION OF THE INVENTION The battery of the present invention includes a through-hole formed at the center of a main battery body so as to be opened to outside. Specifically, the through-hole is formed by winding a strip-shaped positive electrode and a strip-shaped negative electrode about a cylindrical core a number of times with a separator in-between to form a spiral-shaped electrode and mounting the spiral-shaped electrode in a battery vessel having a central opening so that an opening of the cylindrical core is substantially coincident with the central opening of the battery vessel. In the battery having the above structure, the cylindrical core may be constituted by an electric conductor and electrically insulated from the battery vessel, while being electrically connected to one of the positive electrode and the negative electrode of the spiral-shaped electrode so as to be used as a battery electrode. Similarly, the battery vessel may be used as an oppositely poled battery electrode (see Figs. 3 to 7). One or more thin metal plates are inserted into and secured in the through-hole, and additionally radial heat-dissipating fins may be formed around the opening end of the through-hole for further improving the heat dissipation properties. The present invention may be applied to any type of the batteries. However, it is preferably applied to a high-output non-aqueous electrolyte secondary battery. A large-sized non-aqueous electrolyte secondary battery is required to cope with the charging/discharging of a larger currant. For example, a lithium secondary battery employing a non-aqueous solvent is designed to accommodate large current through various improvements because the electrical conductivity of the liquid electrolyte is extremely low as compared to that of the aqueous solution. It is however feared that considerable amount of heat may be generated under the conditions of charging/discharging the larger current. In particular, charging/discharging under the current condition of 2C° to 10C° is possible with the aqueous solution battery, whereas the improved lithium battery may be used only under the condition of 2C° or less. If the latter condition is not observed, voltage drop by the internal resistor and heat generation become outstanding such that the desirable battery performance cannot be displayed. Consequently, by applying the present invention to the non-aqueous electrolyte secondary battery, it becomes possible to effect charging/discharging of the large current. The non-aqueous electrolyte secondary battery may be constructed in any desirable manner. For example, LiM I x M II 1-x O 2 , where M I and M II each denote one of metals selected from the group consisting of Co, Ni, Mn, Fe, Cr and V, may be used as an active positive electrode material, while a carbon material capable of doping and de-doping Li may be used as an active negative electrode material. In addition, TiS 2 , MoS 2 , V 2 O 5 or r V 3 O 6 may be used as an active positive electrodematerial, while metal lithium or a lithium alloy may be used as an active negative material. Furthermore, sulfur and sodium may be used as an active positive electrode material and as an active negative electrode material, respectively. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, preferred embodiments of the present invention will be explained in detail. Fig. 1 is a perspective view showing a columnar-shaped battery of the present embodiment. Fig. 2 is a schematic cross-sectional view showing the inner structure of the columnar-shaped battery shown in Fig. 1. Referring to Figs. 1 and 2, the structure of a battery according to the present embodiment is explained. A battery 1 according to the present embodiment has a through-hole 2 at the center opened on both the upper and lower surfaces thereof, as shown in the perspective view of Fig. 1. The battery 1 is made up of a lower negative electrode casing 3A, an upper negative electrode casing 3B, a cylindrical-shaped positive electrode core 4 and a spiral-shaped electrode 5 having positive and negative electrodes. Referring to Fig. 2, the inner structure of the battery 1 is now explained in connection with the assembling method thereof. In Fig. 2, a battery half is indicated by a reference numeral 1A. The lower negative electrode casing 3A is formed as a cup having a circular opening 6 at a mid part of the bottom thereof. The upper negative electrode casing 3B is planar and has a circular opening 11 at the center thereof, as shown in Fig. 2. The cylindrical-shaped positive electrode core 4 has its length slightly longer than the depth of the lower negative electrode casing 3A, and is provided with an upper flange 4A and a lower flange 4B. A female screw 4C having a length of approximately 5 mm is tapped beginning from the opening end of the inner periphery of the cylindrical-shaped positive electrode core 4 of the flange 4A. The spiral-shaped electrode 5 is formed by winding strip-shaped positive and negative electrodes with an interposed separator a large number of times around the periphery of the cylindrical-shaped positive electrode core 4, so that the positive and negative electrodes face each other with the interposition of the separator. When assembling the battery half 1A, made up of the above-mentioned components, a lower insulator 8 is placed on the bottom of the lower negative electrode casing 3A. On the other hand, a positive electrode lead 7 is welded to the spiral-shaped electrode 5 in the state shown in Fig. 2. The spiral-shaped electrode 5 in this state is mounted on the lower negative electrode casing 3A, by fitting the flange 4B of the centrally disposed cylindrical-shaped positive electrode core 4 in the opening 6 of the lower negative electrodecasing 3A so that the flange 4B is protruded downwards from the bottom of the lower negative electrode casing 3A. The flange 4B protruded downwards is caulked to the opening 6 by means of a lower gasket 9 at P in Fig. 2 for sealing the one side of the battery half. A negative electrode is then welded by a negative electrode lead 10 to the inner periphery of the lower negative electrode casing 3A. After a liquid electrolyte is injected into the inside of the lower negative electrode casing 3A, an upper insulator 12 is placed on the casing 3A. The upper negative electrode casing 3B is placed on the upper insulator 12 so that the upper end of the cylindrical-shaped positive electrode core 4 is protruded via an opening 11 of the upper negative electrode casing 3B. The upper negative electrode casing 3B and the lower negative electrode casing 3A are connected to each other along the outer peripheral surfaces thereof. Finally, the upwardly protruded flange 4A of the cylindrical-shaped positive electrode core 4 is caulked to the opening 11 of the upper negative electode casing 3B at Q in Fig. 2 to complete the sealing. In distinction from a conventional columnar-shaped battery, the battery of the present embodiment has the central through-hole 2 so that it is similar in shape to a cylinder. An aluminum plate 61, 1 mm in thickness, 16 mm in width and 200 mm in length was mounted within the battery winding core 48 as shown in Fig. 3 to provide a sample 1. In addition to the aluminum plate 61, two, four and six aluminum plates 62, each 1 mm in thickness, 7 mm in width and 200 mm in length were radially mounted at equal angles as shown in Figs. 4, 5 and 6, to provide samples 2, 3 and 4. A battery having the inside of the battery winding core 48 remaining hollow was also prepared as a comparison sample 1. These batteries were charged for the first operation to an upper voltage of 4.2 V with a current of 5 A and were discharged to 2.5 V with the current of 10 A. From the second operation on, the current of 10 A was used, and the cycle of charging for 4 hours with the upper limit voltage of 4.2 V and discharging to 2.5 V with the current of 10 A was repeated ten times. At this time, the battery capacity during discharging and the temperature within the battery winding core 48 were measured. The results are shown in Table 3. first cycle capacity (mAh) fifth cycle tenth cycle capacity (mAh) max. temperature (°C) capacity (mAh) max. temperature (°C) sample 1 15.5Ah 14.6Ah 41 14.1Ah 41 sample 2 15.6Ah 14.5Ah 37 14.0Ah 37 sample 3 15.6Ah 14.5Ah 34 14.0Ah 33 sample 4 15.6Ah 14.5Ah 31 14.0Ah 31 comp. sample 1 15.4Ah 14.6Ah 45 14.1Ah 45 Then, with the current of 10 A, the batteries were charged for four hours with the upper limit voltage of 4.2 V and discharged up to 2.5 V with the current of 50 A. At this time, the battery capacity during discharging and the temperature within the battery winding core 48 were measured. The results are shown in Table 4. discharge capacity (mAh) specific capacity (50A/10A) max. temperature (°C) surface area of heat dissipating/surface area of outer peripheral surface of cylinder sample 1 9.3Ah (66.0%) 70 0.10 sample 2 9.5Ah (67.9%) 63 0.20 sample 3 10.1Ah (72.1%) 57 0.29 sample 4 10.8Ah (77.1%) 54 0.36 comp. sample 1 9.2Ah (65.2%) 75 - It is seen from the above results that, if a hollow winding core is used in a large-sized cylindrical non-aqueous electrolyte secondary battery, it is effective to have one or more heat-dissipating thin plates within the inside of the core in order to dissipate heat effectively in large current charging/ discharging operations. A part of the above embodiments exemplifying the invention as defined in claim 1, the following example demostrates how a sealing plate having radial heat-dissipating fins may be advantageously employed for facilitating the heat dissipation and reducing the heat stored in the battery. The battery employed in the present example was the same in structure as the battery of he previous one. However, a sealing plate having heat-dissipating fins is used as a battery lid instead of mounting one or more heat-dissipating thin plates within the cylinder. A sealing plate 71 formed of, for example, aluminum, includes a disc-shaped lid 72 acting as a battery lid, a center opening 73 passed through by the battery winding core 48, and heat-radiating fins 74 arranged radially around the center opening 73 as the center, as shown in Fig. 7. The heat radiating fins 74 are higher in height at the center and become lower in height towards the outer periphery. In the present Example, the sealing plate 71 was secured with a set screw in place of the battery lid 47. Four, six, eight and twelve heat-dissipating fins 74 may be used respectively. The heat-dissipating fins of the sealing plate provide an additional advantage that these may be utilized as connecting points for lead welding during battery connection. If a number of the above-described batteries are used as a battery set, the fact that the heat-dissipating fins of the sealing plate may be utilized as the structure for electrical connection means that ease in electrical connection of the batteries and suppression of heat evolution in the batteries may be realized simultaneously. Thus the properties of control equipment annexed to the batteries may be prevented from being lowered for suppressing accelerated deterioration of the battery service life. As may be seen from the foregoing, the battery of the present invention has many advantages, such as superior heat dissipation or high strength and energy density. Above all, by providing metal thin plates in the inside of the through-hole heat dissipation under conditions of charging and discharging of large current may be achieved promptly, while the manufacture apparatus may be reduced in weight because there is no necessity of separately providing a cooling system in the apparatus.

Claims: A battery (1) having a through-hole (2) in a mid region of a main battery body, said through-hole (2) traversing the main body of the battery and being opened to outside, characterized in that at least one thin metal plate (61, 62) is inserted and secured within the through-hole (2). The battery as claimed in claim 1, wherein the inner wall of the through-hole (2) is used as one of the electrodes. The battery as claimed in claim 1, wherein an electrically conductive ring is connected to the inner wall of the opening end of the through-hole (2) for electrical connection to outside. A battery as claimed in claim 1, wherein said battery body comprising a battery vessel having a central opening as said through-hole (2), and a spiral-shaped electrode made up of a strip-shaped positive electrode and a strip-shaped negative electrode wound about a cylindrical part a number of times with a separater inbetween, said spiral-shaped electrode being mounted in said battery vessel so that an opening of the cylindrical part is substantially coincident with said central opening, said battery vessel being sealed after charging a liquid electrolyte therein. The battery as claimed in claim 4, wherein said cylindrical part is formed by an electrically conductive material and electrically insulated from the battery vessel, and wherein one of the positive electrode and the negative electrode of the spiral shaped electrode is electrically connected to said cylindrical part. The battery as claimed in claim 5, wherein the battery vessel is cylindrical-shaped and has its opening end sealed with a sealing plate (47; 71), and wherein the othere electrode of the spiral shaped electrode is electrically connected to said battery vessel .

Inventors: SUGENO NAOYUKI, TERAMOTO KAZUNORI, SUGENO, NAOYUKI, TERAMOTO, KAZUNORI, SUGENO, NAOYUKI, C/O SONY ENERGYTEC INC., TERAMOTO, KAZUNORI, C/O SONY ENERGYTEC INC.
Applicants: SONY CORP, SONY CORPORATION
Application year: 1994
Main classification: H01M10
IPC codes: H01M10, H01M2